On Dec 23, 6:32*pm, Sam Goldwasser wrote:
Steve writes:
Ok, we got thetransformerin, physically it is smaller than the
other, mounting it shouldn't be a problem. *Without a vacuum tube
plugged in, the regulators maintain regulation down to 100VAC line
voltage. *Now I want to load it to make sure it does in fact have
enough headroom and that thetransformerwon't overheat. *What sort of
load do these tubes impose on the circuit? *

Not much. *For the DV-4D tube used with the VT-4, the heater current is
29 mA at 320 mV, about 9 mW. *So put a 10 ohm resistor between pins
3 and 5 of the octal socket but the power supply won't even notice.

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I guess it's just the light load on the transformer, but a little
12-0-12VCT transformer rated at .085A has no problem giving the
regulators plenty of extra room. At 105VAC line voltage with the
circuit loaded, the filter caps have ~16VDC on them, plenty of room
for a 12V regulator. There is only ~20mA draw on each leg of the
transformer, so it should be happy.
Thanks for the help,
Steve